#include<stdio.h>
#include<ctype.h>
#include<queue>
namespace IO {
	constexpr int bufsize = 230005;
	char buf[bufsize], *f1, *f2;
	char gtchar() {return f1 == f2 && (f2 = buf + fread(f1 = buf, 1, bufsize, stdin)) == buf? EOF: *f1++;}
	template<typename T> void read(T &ret)
	{
		int f = ret = 0;
		char ch = gtchar();
		while(!isdigit(ch)) f = ch == '-', ch = gtchar();
		while(isdigit(ch)) ret = (ret << 3) + (ret << 1) + (ch ^ 48), ch = gtchar();
		if(f) ret = -ret;
	}
	template<typename T, typename ...t> void read(T &a, t &...b) {read(a), read(b...);}
}using IO::read;
typedef long long ll;
typedef unsigned long long ull;
constexpr int maxn = 100005;
int n, m;
char s[25];
bool vis[1 << 20];
std::queue<int> q;
int main()
{
	// freopen(".in", "r", stdin);
	// freopen(".out", "w", stdout);
	scanf("%d%d", &n, &m);
	for(int i = 1; i <= n; i++)
	{
		scanf("%s", s + 1);
		int state = 0;
		for(int j = 1; j <= m; j++) state = state << 1 | s[j] - '0';
		if(!vis[state]) q.push(state), vis[state] = 1;
	}
	int ans = 0;
	while(q.size())
	{
		int t = q.front();
		q.pop();
		ans = t;
		for(int i = 0; i < m; i++)
		{
			int nt = t ^ (1 << i);
			if(!vis[nt]) vis[nt] = 1, q.push(nt);
		}
	}
	// printf("%d\n", ans);
	for(int i = m; i; i--) s[i] = (ans & 1) + '0', ans >>= 1;
	puts(s + 1);
	return 0;
}